S&F Of Cells In The NS Flashcards
Motor neuron (efferent)
A neuron originating within CNS
controls contraction of a muscle or the secretion of a gland
Sensory neuron (afferent)
Detects change in the external/ internal environments
Sends information about these changes to the CNS
Inter neuron
Neuron located entirely within the CNS
Basic structure of the neuron
Soma, dendrites, axon, myelin sheath, terminal buttons
Myelin sheath wrapped around the axon
80% lipid 20% protein
1mm length
Bare portions are nodes of ranvier
Astrocytes
Star like shape Support chemical composition of surrounding fluid Provide physical support Clean up debris Provide nourishment
Oligodendrocytes
Produce myelin sheath on axon
Insulate one axon from another
Found only in CNS
can produce myelin for numerous axons
Microglia
Smallest
Protect brain from invading microorganism
Responsible for inflammatory reaction in response to brain damage
Clean up phagocytes
Schwann cells
In PNS Schwann cells act similar to oligodendrocytes in CNS
provide myelin for only one axon
Entire Schwann cell wraps around the axon
Glial cells
Support/ bind neurons Help to insulate and nourish neurons Myelin production Without this shunting and shortening of nerve implulse occurs MS
Force of diffusion
Molecules will move from areas of high concentration to areas of low concentration
Force of electrostatic pressure
Charged molecules will be attracted to areas of opposite charge and repelled by areas of like charge
Resting potential
- inside + outside Attempt to balance out concentrations of ions Membrane more permeable to k+ Resting potential -70mv Inside is -70mv less than the outside \+ve charge causes depolarisation
Action potential is caused by
Sudden influx of sodium in to the cell ( force of diffusion and electrostatic pressure)
Influx of + signal causes a change in membrane potential
Saltatory conduction to dance
Nodes of Ranvier
AP gets retriggered at each NOR
